Energy utilization in traditional finishing processes may be optimized through the use of innovative technologies.

This article describes how energy costs are incurred and how with simple means and methods maximum
energy utilisation can be achieved through the use of innovative technologies in traditional
finishing processes.

Discussing dwindling resources is no longer relevant today. No matter how alternative
energies are generated, it is necessary to use less energy more effectively.

The parliamentary state secretary at the German Federal Ministry for Economics and
Technology, Dagmar Wöhrl, said during the opening of a congress last year:
"Energy is the motor for economic growth and development worldwide. The conservative use of
energy and raw materials is not only a major factor for climate protection, but also and more
particularly an important competitive advantage for companies and national economies. Using
resources efficiently allows you to produce more cost-effectively than the competition. The
awareness that the best energy is the energy that is not used is gaining more and more
significance, particularly in the light of the ever-increasing energy and raw material prices."

Where Do Costs Occur, And How Can They Be Measured?If one considers the tenter as one of the main dryers used in textile finishing, then certain
demands are made on this dryer and its configuration.

If your tenter meets these requirements, you have already taken the first step in the right
direction.If one considers the classic tenter drying process, one can see here how much heat energy
is required to dry a damp textile
(See Figure 1).

Figure 1

The damp textile web enters the tenter at production speed and is heated. The
water is vaporized and evaporates. The dried textile leaves the tenter with a certain residual
moisture content and at a certain temperature.

The evaporated water is absorbed by the circulating air. Part of this moist air is drawn out
of the machine as exhaust air and is replaced by fresh air. This fresh air has to be heated to
drying temperature. The energy required to evaporate the water, heat the fresh air and compensate
the losses is supplied to the machine by the heater with the circulating air serving as energy
medium. A small part of the energy is normally fed into the system by the rotating fan blades of
the circulating air fans.

This can be expressed by the following formula:

The process heat flow and the heat flow to heat the fresh air are the most
significant elements in the drying process.

The process heat flow is here the most important heat flow for which energy has to be input:

The specific energy consumption for each application can then be calculated using
the following formulae:

From these calculation bases, it is possible to determine the specific energy
consumption per kilogram (kg) of textile during the drying process in the tenter as a function of
the water volume to be evaporated — the parameter is the drying temperature
(See Figure 2).

This then gives the following hourly energy consumption during the drying process:

The enormous influence of the initial moisture content on the drying process is
shown below, again from a different perspective for emphasis
(See Figure 3).

The graph shows the effect of a variation in the initial moisture content. The
starting point is 70 percent. A reduction in the initial moisture content results in an increase in
production speed and a reduction in energy consumption and production costs. An increase naturally
results in the opposite effect. Overall costs and thermal energy have practically the
same-percentage relative deviation.

In summary, this means first of all that the greatest contribution to energy savings is made
by a reduction in the initial moisture content. Wherever possible, alternative liquor application
systems should be employed. The liquor application should be as low as possible, but as high as
necessary.
Examples Of Cost Reductions During The Drying Process

Figure 5: Monforts’ soft-coating production range enables energy usage and drying cost
reductions as well as increased production speed, among other advantages

Figure 6: A tenter inlet section with various upline elements

Final ConsiderationsThis article is intended to show where the problems lie during drying, and how maximum energy
utilization can be achieved with simple means and methods through the use of innovative
technologies in traditional finishing processes. Energy efficiency is a step in the right
direction. What can be eliminated doesn’t require disposal, and what isn’t applied doesn’t require
drying.

In order to optimize work flow, older-generation dryers can be redesigned electrically to use
frequency controllers, high-efficiency motors and measuring instruments. It is very important to
reconcile economy and ecology by using affordable technology to reduce energy consumption and costs
and reduce wastewater.